(Investigator's Abstract): A two phase project is described which will permit extending the performance of 64-128 channel EEG telemetry systems which are normally used for long-term monitoring of patients with indwelling intracranial electrodes. The extended performance will include functional mapping (FM) of cortical areas of the brain by three techniques: recording behavioral response to electrical stimulation of intracranial electrodes, evoked potential mapping and functional-MRI. The final product will combine this functional mapping with existing techniques for the mapping of regions that are dysfunctional by reason of epileptiform electrical activity and integrating the display with anatomical mapping via MRI or CAT to provide a complete, integrated workstation for evaluation and surgical planning for epilepsy. A major advantage of the proposed system is that it will be designed to economically "Piggy-Back" additional clinical functions on a large, already installed base of high-resolution monitoring systems, without disrupting their primary clinical function of detecting and recording epileptiform events.